ML18025A663
| ML18025A663 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  |
| Issue date: | 09/18/1978 |
| From: | Curtis N Pennsylvania Power & Light Co |
| To: | Grier B NRC Region 1 |
| References | |
| Download: ML18025A663 (10) | |
Text
REGULATORY INFORMATION DISTRIBUTION SYSTEM (BIDS)
DISTRIBUTION FOR INCOMING MATERIAL 50-387 REC:
GRIER B
H NRC ORG:
CURTIS N
W PA PWR Sc LIGHT DOCDATE: 09/18/78 DATE RCVD 09/22/78 DOCTYPE:
LETTER NOTARIZED:
NO COPIES RECEIVED
SUBJECT:
LTR 1
ENCL FORWARDING FINAL CONSTl UCTION DEFICIENCY REPT CONCERNING DEFICIENCY IN CARRIAGE BOLT FASTNERS USED ON'80 VOLT MOTOR CONTROL CENTER BUS SPLICES.
PLANT NAME:SUSQUEHANNA UNIT 1
. REVIEWER INITIAL:
XJM SUSQUEf lANNA UNIT 2 DISTRIBUTER INITIAL~I~
+4+4cc++4+4<<4>444+
DISTRIBUTION OF THIS MATERIAL IS AS FOLLOWS NOTES:
SEND ISE 3CYS FSAR 5; ALL'MDTS.
CONSTRUCTION -DEFICIENCY REPORT (10CFR50. 55E)
(DISTRIBUTION CODE B019)
FOR ACTION:
INTERNAL:
ASST DIR VASSALLO~<W/ENCL PRed~o
'NER>%4l/ENCL REG F NCL h E>+W/Z ENCL'OSSIC<Y 5 STAFF4+W/ENCL DIRECTOR DPM++W/ENCL QAB~<<W/ENCL AD FOR ENG4+W/ENCL-AD FOR PLANT SYSTEMS>+W/ENCL STANDARDS DEV. >ccW/ENCL FERD DREHER/IE4+W/ENCL BR Cl.lIEF LWRN3 BC+<W/ENCL LIC ASST LWRN3 LA++W/ENCL, NRC PDR>+W/ENCL OELD44W/ENCL MIPC~<<W/ENCL DEPUTY DIR DPM++W/ENCL DIRECTOR DSS++W/ENCL AD FOR REAC SFTY++W/ENCL AD FOR SYS 8c PROJ++W/ENCL I
SEYFR IT/IE44W/ENCL EXTERNAL:
LPDR S WILKES BARREi F'A++W/ENCL TERA~<<W/ENCL NSIC.~+W/ENCL ACRS CAT B~~W/16 ENCL ENCL 41 DISTRIBUTION:
LTR 41 SIZE:
2P+7P 44W4%%%%%%4"X+%%%%
<<4"<<<<4 54%WW%%4cc%4%%
CONTROL NBR:
78086 144
/N ~
THE END cc%4%4%4'ctwcc%%%%wct4%%%%%%%%%%0%%4%0
NORMAN W. CURTiS Vice President. Engineering 8 Construction 821-5381 Septattber 18, 1978 PPaL TWO NORTH NINTH STREET.
ALLENTOWN. PA.
TRIRT PHONE: (2IS) 22/-Sggg 8O~~
qQS
Ãr. Bcryce H. Grier Diret~-.
Region I U.. S. Nuclear Regulatory Gmaission, 63I. Park Avenue.
King of Prussia,, Pennsylvania:
17406; rn SUSQUEfRHNL SZE2M ZLH'TRIC STATICN FINAL REPORT'PEPXCIENCY IN CARRIE BCLT 1RAKZNERS USED CM 480. VCLT'ZLtCR,CONTROL. C5RITER BUS'PLICES DOCK'T, KS:
50-387/50-388 LICENSE NOS:
CPPR-,101/CPPR-.102'Rs-100450/10050&
'IZZ840M
- 'PZA-290
'ear 8r. Grier:,
Attached,'is. a Definitive Repart of the-subject deficiency as required by 10CPR50.55 (e)
On:August 8, 1978,, O'.. Green, PPEZ. Resident Nuclear Quality Assurance Engineer/, advised'r..
R Gallo ~ Reactor Inspector,.
NRCP Region I,. that PP&L was in, the process of'valuating the repart~ility of the subject deficiency.
Coincident with PP&L's verbal advisory to the CcmnissionBechtel Quality Assurance issued ~-1-27 (Ranaganent, Corrective Action Report) requestirlg that Bechtel Project Engineering make a detexmination regard~ the re1xxrta-bilityof the deficiency.
The determination, affirming the r~ability of the deficiency, was made on Aut3ust 23, 1978'nd.'s: the basis for the attached-fina1'eport.
The defective, materfa1 is. being controlled;. and'i11. be corrected and closed.
aut under'he provisions of the Bechtel Quality Program.
Please, achrise should you recguxe other information.
Very truly,yea~,
N. W. Curtis Vice President-Engineerizg
& Constlxmt~n ARS:mcb Attachment 7 ~gP~&0144 PENNSYLVANIA POWER 6
LIGNT COALPANY
8~rtemher 18, 1978 cc:
Hr. Z.. G. Davis (15)
Ecting Director-Office of Inspection
& Eafarcenent U. S. Nuclear Rec~latozy Ccmnission Nastdz~n, D.C.
20555
Ãr. G.. WDonaM,. Directar (1)
Office of Management Information 6 Program Cantxo1 U. S. Nuclear Regulatozy Ccnmissian Wa.'~~n, D.C; 20555 Br E~~ M Ga11o.
'P"0
. Box 52'Eu.cRshixug~ Pennsylvazua I8655.
FINAL REPQRT QP A DEFICZERKY IN CAEB32GE BOLT'ASTENERS USED QN 480 VOLT HCGXE CQNTRQL CE5TER BUS SHZCtX FOR THE SUSQUEHANNA STEAM ZZZCTRZC'EQXGN:
D. P. Parsons.
SSES: Electrical, Group Supvr.
Apgrovecb By:. N
~,~'
~ g s A. N..
e Supervising EngineerWesign-Susquehanna Revh~:
A R
Manager-Huclear Quality Assurance PENNSYLVANIA, PONER 6 LIGHT CCMPMY.
ALUMUNNq PENN'i~V2QGK RMXMB1&18, 1978
'INhL.
REPORT'P" CMEGAGE BCLT DEFICIEtKY CN 480V MXXRCONTR%
CEDER HJS SPLICES' P.O.. 8856-E-I'18 AC SUSQKHANNA, STE2K 3KZCZRIC'I2QXCN UNZES: 1 6-2
TABLE'F CONTENTS Introduction Description of the Deficiency.
Analysis of Safety Xmplications Corrective Action Conclusions.
Pg.
1 Pgs 1,.2 Pgs
~,
2g, 3
Pgs
~
3g 4
Pg..
4
GRABz~ is pres~JBK in with the recg.xiranents of Title 10, Code of Federal Ebagulations, Part
. 50, Section. 50.55(e).
A deficieI~ in. equigaent supp~ by Cutler-samer, tnc. was discovered
't:I '~~
th Steam El;ectric Station.
(SSES);
V PP&L's'jh-Constructar (Bechtel)'~ in the course of.
'll Il which are usecL to splice-bus sections at, the shipper@, splits of 480 volt.
aetatr conhn1 center units, noted'he occurrence of ~reral cases of thread fait;ures (stripped threads): while, toxqtxing the bolts..
The'aiI.ures and. their cause were assessed far their impact on the safety of the'pexwthn. of'he'lant.
Based: upon an evaluation, of the safety implications, Bechtel Engineers@
has concluded that. the condition is rep.zetahle under 1.0CFR50.55(e)'ecause, were it to have ranainecl
, the condition could have adverse affects on the safe operation of the plant.
CF'HE DEFICIENCY
~ desist of Susquehanna Units 1 a 2 prcmides for 28 safety related 480V stator control centers.
Durizg the ixmtallation of these 480V avatar control center sections, it. was noted that the 3/8" carriage bolts supplied for
Gv>~Ling the-480V bus splice plates were experiencing randan thread failures when tarxpxed to a~xmriaately 1&ft./lbs.
Tzrvestigation of these bolt failures revealed the following facts:
1..
Gha 3/8" dzaraeter carriage bolts supplied ky Cutler-Hanmer for use in the 480V bus splices were supplied's a mixed pac&~ with 1/4" thic3< arxL 3/&>> Crick rruts.
2.
II
" '8
'~by t1 f
tl of the 480V'MCC's. did not" specify the proper ccrobinatzon of fasteners to be used: far the bus splices;. thereby pezmitting 3/8"'arriage bolts to beroatecLwith.l/4" or 3/8" thick rnzts.
Zn addition, the zzzstzmction manual did not provide values far torcpxiz~ the 3/8" carriage bolts.
3 Allof the bolt; threacL failures whiiah were detected; occurred when a 1/4" thick nut. was utzI'ized'n cardunatian-with
- a. 3/8." diameter carriage bolt.
Qxtler-Hatmier was apprised'f the above information., and they advised that: the correct spli;ce. fastener. was a 3/8" carriage bolt: with a ful1 3/8" Crick rrut topped. to 18ft;flbs.
The carriage bolt thread. failure has been detezznined to. have been caused by the undersized (1/4" thick) "jam" nuts..
AKKYSIS'F GAUZY lMPXZCKTIONS The 480V nestor control systan design: was reviewed and the following was concluded far the worst condition, including a postulated seianic event:
The deficiency, which izrvolves the. actual stripping of threads on same of the carriage bolts., is concealed by washers and the nuts used, to fasten the bolts. If undetected, or uncorrected, this condition cauld perdu.t tb-re,tzng surfaces, of the bus and. the bus splice plates to be loosely joined at a point which was designed to caz.'ry 600 amperes of load current.
!M ~,
! I
'll!~p *'!
which cxaQB result in a fire or bus failure and the loss of the mtor cantxaL center.
In those cases where actual thread stripping had't occuxxed, the undersized nuts may have~aar~Mess, caused sufficient overstress an the carriage bolts. that an incipient failure of the threads cauld'cist Adchd. farces. fnm, a seisnuc event cauld cause overstressed
.bolts to fail~ Ioosenizg the bus joint.
Such. events cauld result in the situatian. described, in the preceeding: paxagxaph Since thread stx~>ing ar incipient: threaX. stripping of these, caxriLage.
bolts. is; a xan8an event and could; occur in any ar all of the safecp;anis.
abator" contxol centers, the. possihiLlity.of. a ccmnan aade failure exists.
The'simu1taneaus loss:of redid-mt motor cantxol center feeds, which serve vital safety related. loads, cauld result in a safety hazaxd'o-the operation of the plant.
, ACTION TAKEN'O CCNTEE, THE DEFICIENT ZZEMS Bechtel Quality Contxol issued Noncanfoxmance Bepaxt No. 2855'n 8/2/78 to identic and. contxol the 480V HCC's (twenty) presently on. site for the carriage bolt deficierxy beiing rep:Med.
Bechtel QA generated Managenent Corrective Bat~n Recpmst No. 1-27 dated August 3', 1978 in axder to obtain documented evidence of Bechtel Project
I Itt
&tl 55',tl I ~ tt ~
' ~tr I
1005(50.55( I.
PZTICN K) RES(AVE THE DEFICZEKY'utl~hmner willreplace all cazwiage bolts and rnxts used for splicing links at shiippiap spLits on MCs with 3/8" bolts-and 3/8" thickness nuts far all.
MCCs alzxeiLy izzst. II'ed,. willreplace 1/4" znxts. with full nuts (3/8") far MCs that: are not yet inst-Q1ed, and'iII: utilized, 3/8" thick nuts far MZCs.
curxmxtIy being, mantxfacttxzxd' (This. was docUmented'n
- a. THK'nxn Cutler-Hanmer to. Becht~ dated 8/28@78.)'utler-Kzmer has-updated the 480V IKC 1~:tl I
5 ~
. (1550.(I!
tranaoitted'. a revised. instruction.ztanuaI to the Bechtel field forces.
~'CGRZVSICNS'ith the replacement of a11. 3/8 carriage bolts. and nuts-on all the bus splices of aU. aator contxol centers already delivered to the SSES site with correct 3/8" bolts and 3/8" t&cJc nuts, with the correct= torque@. of these.
fasteners to 18 ft.. lbs., and'ith. all futnre actor contxol centers being.
supplied with correct. hamhare, the rendu;irenents of Specification 8856-E-118 Revision 6, Pcuagraph 9.2.1 willhave been. met; the deficiency will have. been coz~cte3,;
and. the potential'afety hazard. wil1.have been elizninated.
The Bechtel generated 5'onconforroance Report (NCR No 2855) will'otbe closed uzztil there is Quality Control verification that the 480V'KXa bus splices have been caapleted in accozxhnce with the design and vezxhr recpxirenants and the attendant inspections have been accaap1ished.